he United States
along the Mexican border.

All non-ruminant ungulates have from four to six incisors in the upper
jaw; the canines are present, and sometimes, as in the wart hogs, reach
an extraordinary size.

Coming now to the ruminants, all digits except the third and fourth have
disappeared from camels and llamas, and the nails on these are limited
to their upper surface without forming a hoof, the under side being a
broad pad, upon which they tread. No camel-like beasts have inhabited
North America since the Pliocene age. Chevrotains, or muis deer
(_Tragulidae_), are not deer in any true sense, as they have but
three compartments to the stomach; antlers are absent and in their place
large and protruding canine teeth are developed in the upper jaw, and
the lateral metacarpal bones are complete throughout their length,
instead of being represented by a mere remnant. They are the smallest of
ungulates, and inhabit only portions of the Indo-Malayan region. Camels
also have upper canines, and the outer, upper incisors as well.

The giraffe is separated from all living ungulates by the primitive
character of its so-called "horns," which are not horns in the usual
sense, but simply bony prominences of the skull covered with hair. Some
of the earliest deer-like animals seem to have had simple or slightly
branched antlers which were not shed, and which there is reason to
believe were also hairy, and in these, as well as in other characters,
giraffes and the early deer may not have been far apart. The "okapi,"
Sir Harry Johnston's late discovery in the Uganda forests, seems to have
come from the same ancestral stock, but the giraffe has no other
existing relatives.

The true deer, to which we shall return, are readily enough
distinguished from the ox tribe and its allies by their solid and more
or less branched antlers, usually confined to males, and periodically
shed.

So, through this rapid survey, we have dropped out of the hoofed beasts
all but the bovines and their near allies, and are thus far advanced
toward our definition of a bison, but from this point we shall not find
it easy to draw sharp distinctions, for while the _Bovidae_, as a
whole, are well enough distinguished from all other animals, their
characteristics are so much mixed among themselves that it is hardly
possible to find any one or more striking features peculiar to one
group, and for most of them recourse must be had to associations of a
number